Apparatus for the regulation of current in an electrolytic cell



March 13, 1951 R. J. FERRET-BIT 2,545,412

APPARATUS FOR THE REGULATION OF CURRENT IN AN ELECTROLYTIC CELL Filed-Oct. 29, 1945 2 Sheets-Sheet 1 March 13, 1951 R. J. FERRET-BIT APPARATUS FOR THE REGULATION OF CURRENT IN AN ELECTROLYTIC CELL 2 Sheets-Sheet 2 Filed Oct. 29, 1945 Patented Mar. 13, 1951 UNITED STATES PATENT OFFICE APPARATUS FOR THE REGULATION OF CURRENT IN AN ELECTROLYTIC CELL Application October 29, 1945, Serial No. 625,388 In France April 7, 1944 Section 1, Public Law 690, August 8, 1946 Patent expires April '7, 1964 4 Claims.

This invention relates to electrolytic cells and more particularly to such apparatus in which several electrodes are connected in parallel to one pole of the power source.

Heretofore it has been known that the operation of electrolytic cells can be regulated by the adjustment of the distance between each anode and cathode, so that the current flowing between each such set will be a desired amount, usually the same as that flowing between other like sets of electrodes in the apparatus. If the sets of electrodes are mounted in parallel in the power circuit, all the anode-cathode sets will have the same voltage applied to their terminals. In each circuit from anode to cathode through the elecrolyte, the current is determined by Ohms law to be the voltage applied to the terminals minus the electromotive force of the cell divided by the inter-electrode resistance between the anode and the cathode. During operation, then, it can be seen that the current will vary, since the impressed voltage and the inter-electrode resistance will vary, giving either an uneven deposit on the various electrodes or excess heating with resultant drop in yield. This can be overcome by adjusting the inter-electrode distance to keep the current constant at a desired value relative to that flowing between other electrode sets; however, this is not easy to do since the current in the main power circuit usually varies considerably. Thus, an ammeter in each electrode circuit would be useful to bring about even depositing on the several electrodes when its reading was correlated to the current flowing in other electrode sets and in the main power source. The applicants invention resides in such a correlation by automatic means.

One object of the present invention is to provide an apparatus for obviating the difliculties of the prior art as recited above.

Another object of the present invention is to provide a device for signalling the existence of a difference between the actual value of the current flowing through an electrode circuit and the desired value of this current relative to the current flowing in other electrode circuits.

Still another object of the present invention is to provide means for operating an automatic adjustment device whenever the relative value of the current flowing through an electrode circuit differs from the value it should have.

Other features of my invention will result from the following detailed description of specific embodiments thereof.

The preferred embodiments of the present in- 2 ventionwhich will be hereinafter described, with reference to the accompanying drawings, are given merely by way of example.

In the drawings:

Fig. 1 is a diagrammatical view of an apparatus according to the invention of the applicant for the measurement of the ratio of the current flowing through an electrode circuit and the total current in the power circuit.

Fig. 2 is a diagrammatical view of an apparatus according to the instant invention for signalling and controlling the existence of a difference between the current actually flowing through an electrode circuit and the value of the current that should flow therethrough.

Figs. 3, 3a, and 4, respectively, are views relating to two other embodiments of the invention.

According to my invention, in order to measure the differences which may exist between the current actually flowing through an electrode circuit and the current that would flow therethrough when the total current fed to an electrolytic cell is uniformly distributed to the electrodes thereof, I do not measure the current flowing through each electrode circuit. As a matter of fact, such a measurement would not give the desired indication, because variations of this current may be caused, not only by an unequal distribution of the current between the various electrode circuits, but also by a variation of the value of the total current in the power circuit. To overcome this difiiculty I provide a unit, generally designated 32, for measuring the relationship between the current fed to each electrode set and the total current fed to the electrolytic cell 3|.

For this purpose I make use of a balanced relay generally designated 33 having inductance members such as cross coils I and 2, said relay being of a known type. One of the coils or windings, say l, is subjected by means such as shunt 3 coupled with power lead Hi to a voltage proportional to the current flowing from power leads 14 by way of a main lead 35 through the electrode l0, while the other winding 2 is subjected by means such as shunt multiplier 4 connected to the main lead 35 to a voltage proportional to the total current.

Other devices, such as direct-current transformers, may be used which respond with a voltage that is proportional to the current flowing in a circuit to which they are attached. Since most of these devices, except the shunt, give a fairly high voltage, when they are used with coil 2, one device may serve a multitude of coils 2, one for 3 each electrode set, through a series of potentiometers 5.

With such a relay, the deviation angle through which the coils turn is such that:

-fl tangent 0- where on is the ampere-turns of coil l and an the ampere-turn of coil 2.

Now, if i is the current fiowing throughan electrode circuit under consideration, andlthe-total current fed to the whole electrolytic cell, then a1=K1i and a2=K2I so that Q i tangent 0- I If, by means of potentiometer 115, we adjust the values of K1 and K2 so that n being the number of individual-electrode sets in the apparatus'then tangent 0 :11

The apparatus will, therefore, indicate the ratio of the current flow in theelectrodethatis being considered to the desired current that should flow therethrough, which is usually-I/n.

The actuated member of the relay will engage connections 6 or ,7, depending on the movement of coils I and 2 and will actuate on adjusting means 30 for adjustingthe inter-electrode space, said adjusting means comprising a motor, for instance.

In the embodiment illustrated in'Fig.:2 for use with a cell 3|,I make use of units '32 having a balanced differential relay '33 and, having two coils II and I2 wound so that-their'fields-act in opposition. One of the coils H has impressed upon it a voltage proportional to the current flowing through the power lead 14 attac'hed to the electrode ill that is under cons'iderationthis voltage being obtained through a means such as shunt 3 coupled with a power lead 584,.as shown in the drawing, or a-direct current transformer of 'a type well-known. Coill Zlhas impressed upon it a voltage proportional Ito the current flowing through 'the total cell circuit, this beingobtained by a means suchas shunt multiplier 1 connected to a main lead 35 through which current passes to the power leads M. As in theembodiment'of Figure 1,.if the device :for obtaining a voltage .proportional-tothe currentgfiowing through the main power circuit'gives a high enough voltage, it maybe used'in conjunction with potentiometers 5 to serve all the coils 12 where a plurality of electrode setsare present.

Two'opposed springs, notshown, aredisposed so that, when the driving torque on the actuated member 34 of the relay, due to the coils,.is zero, said actuated member is'inintermediate position .betweenthe connectionsfi and i. ,If this torque is either-positiveor negative, the'actuated memberof the relay may cooperate with either connections 6 or connections 1 accordingas the dif- .ference between the ampere-turns of coil l .and the ampere-turns of coil 2 is positive or negative.

4 If m designates the ampere-turns of coil I and a2 the ampere-turns of coil 2,

(Zl -LKli and a2=K2I ii being the current in the electrode, and I the total currentin the electrolysis cell.

Therefore, where .e is difference between the strength of1the electromagnetic fields of the wind- 'ings,

e=a1--a2=K1iK2I If,by means-of potentiometer 5, we adjust the 'values of K1 and K2 so that:

K1=7LK2 n being the number of electrodes, then .and when the current V1' in vtheeelectrode that is being considered 'is at the desired value, usually I /n, the difference 6 isequal tozero and theactu- ,atedmemberof therelayisbalanced in theintermediate position, with both connections Band .1

open.

When :is smaller .than I /n, connection .6 .is closed, and when 2' is ,greater than ,I/n, connection 7 is closed, irrespective ,of the ,value of .the ,total current :intensity. According .to whether connection 5 ;or =1 .is closed, the-adjusting means 30 willcperate-tomake the inter-electrode space shorter or. longer, with a corresponding increase or decrease ,of current through the particular .anode-cathodeset-adj usted.

Fig. ,3 sho.ws anothercmbodimentof a device according to the ,invention .for signalling the existence-of a difierencebetweenthe actual value of the current flowing ,throughan electrode and .the value that this current should have, this device .being intended .either to permit manual ccontrolof the resistance corresponding to this electrode or .to control the adjustment of this :resistance automatically.

Inthisunitfenusewithan electrolytic celtdevice, aninductance. member such as magnetic coil ,or core 13 .is coupled with power lead it connecting the electrode to the current feed. The magnetic core J3 {carries an inductance member such asxa coil -l5-.whose windings aresuch as to induce ,in the core onelectromagnetic fiux op- .posite :to the :flllX induced in said core by the current flowing in the ;bar M. \In said 0011 i5 ,is carried-a current broughttoit by.a ,means such .as shunt multiplier Al, or similar device connected to the main lead 35 and responsiveto the amount of current flowing in .the .main power circuit. If c1 designates .the ampere-turns .of the coil 15 and i the current fiowingthroughthe bar SM, the

.flux inducedinthe magnetic core !3 will be zero when:

With a shunt multiplier s, shown inthe drawr ing, or a direct current transformer having a transformation ratio m,--t-he-current ia'fBd to coil 15 is:

Now, if n iszthe:number'oflelectrode circuits of ;the electrolytic .c ell,;and if the number of turns, N,,of .coil;l,5 is chosenin-suchmanner that:

then the flux induced in the magnetic core l3 will be zero when m n m 11 When i is greater than I/n, the resultant flux in magnetic core I3 is in one direction, whereas, when i is smaller than I /n, the flux is in the opposite direction.

Indication of the existence and direction of this flux is obtained through a balancedrelay generally designated 33, comprising a magnetic cylinder 18 having its axis perpendicular to central bar i4 and carrying a winding l1 traversed by a current supplied from coil l5, as best shown in Fig. 3a. The flux produced by the current flowing in the coil i! reacts with the flux induced in the core I 3 when there is a difference between the flux induced in core I3 by the current in the bar I4 and the flux induced in core l3 by the current in the coil Hi. This produces a rotational couple upon the cylinder 16, dependent on the direction of the resultant flux in core I 3.

Two opposed springs 48 and I9 yieldingly oppose rotation of cylinder 5 about its axis, so that in the absence of a substantial resultant flux in magnetic core 13, element I6 is maintained in a determined position of rest, corresponding to movable coil I! being located in the plane of magnetic core l3.

The axis of movable cylinder l6 carries an actuated member adapted to cooperate with connections 6 and I, which may be connected either with signalling means or with automatic adjusting means not shown. Relays of the type just above described may be utilized in combination with auxiliary or delayed-action relays according to the amount of current to be supplied through their contacts and the small variations in current that should have no effect on the system.

In Fig. 4 is shown a series of units generally designated 32 an embodiment of my invention to be used when, for some reason, it is not possible to make use of the ohmic drop along each electrode conductor, as in the above described embodiments. In this case, I make use of the fact that a variation of reactance takes place in a coil mounted on a magnetic core when direct current ampere-turns are superposed on the alternating current ampere-turns existing in this coil. Each of the power leads [4 connecting the electrodes ll! of the cell 3| with the current feed through main lead 35 has coupled therewith a means such as a magnetic core 2|, which may be shielded to protect said core against the parasitic action of the other conductors. The windings 22 wound on said cores 2| are fed in series from a source of alternating current. In the absence of direct current being impressed thereon, the current flowing in these windings 22 is the total voltage U divided by the sum of the reactances of the coils mounted on n magnetic cores 2| (n being the number of electrode sets in the apparatus), the ohmic resistance being very small compared to the reactance.

If all the cores and windings are exactly identical, the voltages, U1, U2 Un, across the terminals of said windings will be such that:

If direct current is caused to flow through each conductor connected to the electrode ID, the reactance of each of the cores will be reduced, due

to the saturation produced by the action of this direct current, but, if this action is the same for all of the cores, that is to say, if the currents passing through the n electrodes are equal, the same relation between voltages ur, uz an, and U is preserved.

However, if there is an unequality in the distribution of the current among the electrodes, the voltages in question are no longer equal to one another, although their sum is still equal to U. It should be noted that it is possible that U may remain constant, and in that case, the alternating current flowing through the windings will be variable in accordance with the react ance of each magnetic core. I may also arrange to have current i substantially constant, which will place these circuits under better magnetic conditions, but will cause voltage U to vary, the above equations remaining however unchanged.

In order to indicate variations in distribution, I make use of balanced differential relays 23'of a known type, each having two inductance members such as movable coils 25 and 26 located in the field of a permanent magnet. On one of these coils, 25, is impressed a voltage propor'- tional to the voltage in its respective coil 22, this coil voltage being rectified by a rectifier 29 before being impressed on the coil 25. The other coils 26 of the relays are all connected in series and subjected to the voltage U rectified first by a means such as rectifier 24. V

This device will work in the following manner:

If an designates the ampere-turns of coil 25 and as the ampere-turns of coil 26, according to whether difference 5 is positive or negative, the force acting upon the actuated member 34 of the relay, which force is proportional to this difference, will be positive or negative. Then either connection 2'! or 28 will be closed depending on the direction of movement of the actuated memher, while, when the difierence in'question is equal to zero, both of these connections 28 and 21 are open. The closure of one of the connections will, of course, actuate the adjusting means 30 for changing th inter-electrode space.

Considering one electrode I0,

IZ1=K1U1 n being the number of electrodes of the electro-:

lytic cell that is being considered, Therefore,

If the system is constructed in such manner. that K1:K2=K, then:

Then the actuated member of the relay will be balanced in intermediat position, with con; nections 21 and 28 open when But, at this time:

u1=f1uto fi representing the function existing between in, th current f1 flowing throughv the electrodethat is considered; and "the alternating :current: irfi'owing 'athroiigh the windings of all the :circuits rlf z-allzthe unagnetic circuits are identical, ithen:

11:12:13 a. :fnz'

Since on the other hand,

Ml-i-l'I-LZt-l-UG-I- ;u =U

then,

Sfi(11,1i) -Hf(-12, Ii) +f(-I1i, i =U Since current "i is the same for all the winding circuits, if

As'the relayisbalanced when then at this time:

:In other ,words, the .actuated member of the relay is .in a Jieutral position when the direct current flowing through the electrode that is being considered .is equal .to the total current divided by the number of electrodes. On the other handbone of the connections will'be closed if I1 is smaller than 'I/n, while the other connection will'be closed if I1 is greater than 'I/n, and this irrespective of the value of alternating current ,I2' and ofjfunc'tion I, provided that:

in other words provided that all the windings 22;and=.cor.es :2 I :are:identical.

The :devices above described permit anticipating :anode effects by arranging the parts in the relays so thatiaction takes place for a predetermined difierence between the .-normal current that is to flow through each electrode set and a current substantiallydifierent from this normal current because of 'such effects. It has been noticed that, in electrolysis cells undergoing anode ,efiect and which include several electrodes, polarizingidoes not takep'lace simultane ously for all the electrodes,but, on the contrary, a short tim befor the total anode effect, polarization takes place for one of the electrodes. The apparatus arranged according to the invention permits anticipating the anode effects by providing two series of contacts, the first series being closed for small variations from a state of equilibrium and serving to adjust the interelectrode space, while the second series responds to an important reduction of the current flowing in one of the electrodesyto warn-that anode efiectwilloccur in'a short time.

I may make use either of apparatus having two sets of contacts, as described above, or two sets of relays, etc., for each electrode, one of these sets being adjusted in such manner as to have its contacts closed for relatively small current variations, the other adjusted in such manmen as to have its contacts-closed for an important reduction of the current on one electrode.

iIt is alsopossible. according'to the present-invention, to "provide this I second series of connections or this second ;-set of relays, etc.,-on only one of the electrodes, provided the .-latter :is adjusted in such manner that the current flowing therethroughrispermanently higher than the current flowing through each of the other electrodes, which causes electrolysis to take :place more :rapidly in the zone of the bath corresponding to thatelectrode, wherebypolarizationalways starts first on the electrode in question.

(In :a general manner, uwhileilhave, in athe above description, disclosed what .'.I deem --.to :be practical and efficient embodiments of the present invention, it is to :be understood that I 'do not Wish to be limited ithereto, since changes may be made in the arrangement, disposition, and form of :the ,parts without "departing :from the principle of the presentinvention as defined by the accompanying. claims.

Having thus described .my invention, whatI claimas new and desire .to secure byFLetters :Patentzis:

.1. Anelectrolytic-apparatus havingat leastone cell for containing :an electrolyte and having .a plurality of units each comprising two "electrodes immersed in said electrolyte, adjusting means for moving :one of .said :electrodes toward "and away from the other electrode, power leads attached to said :-electrodes for connection through a main lead with a direct-current source, -a balanced relay in each unit having two inductance members Whose electromagnetic :fields are .in opposition anda member actuated bysaid inductance members, said actuated member :moving .:'between a connection for causing the adjusting means to move the said one electrode :away from the 1 other electrode and a zconnection'for causing said .adjustingzmeans :to move ithe said one electrode toward the other aelectrode, means :coupled with the .power lead :of oneo-f said electrodes for impressing on one .of said inductance members a voltage proportional to the current flowing through said electrode, and means connected to the main lead for impressing ':.the :other of said inductance members a voltage proportional to the .currentzflowing through all of the units.

12. iAn.electrdlyticrapparatus as recited inclaim 1, wherein: .a coresurroiundsithe power leadand has a, .gap at one 'part thereof, the electromagnetic field existing :in said gap acting on said actuatedlmember :i or the:movementithereof.

3. An electrolytic apparatus as:.re.cited:in claim 1, wherein: said means coupled with the power lead of one of said electrodes compr'ises .zaymagnetic core surrounding said power dead, a :winding on said corenneansfforconnecting said winding to asource of alternating current, said-winding being :connected touonesi'de-of a.rectifier,'the other side of which is connected to said induct ance member.

4. An electrolytic apparatus having at least one cell "for containing an electrolyte and 'having a plurality of units each comprising two e1ectrodes immersed in said electrolyte, adjusting means 'for moving =one cf said electrodes toward and away from the other electrode, power leads attached to said electrodes for'connectionthrough a main -lead with 'a direct-current sourcega balancedrelayyin each unit having two "opposed 'actuating coils and an actuatedm'ember, said actuated member moving between a connection for causing the adjusting means to move the said one electrode away from the other electrode and a connection for causing said adjusting means to move the said one electrode toward 'the other electrode, means coupled with the power lead I of 9 10 one of said electrodes for impressing on one of Number Name Date said coils a voltage proportional to the current 1,547,984 Weber July 28, 1925 flowing through said electrode, and means con- 1,587,106 Edelman June 1, 1926 nected to the main lead for impressing on the 1,849,838 Kennedy Mar 15, 1932 other of said coils a voltage proportional to the 5 1,917,657 MacChesney July 11, 1933 current flowing through all of the units. 2,150,015 Witham Mar. 7, 1939 ROGER JOSEPH FERRET-BIT. 2,213,099 'Adorjan Aug. 27, 1940 2,248,504 Kenny July 8, 1941 REFERENCES CITED 2,357,524 Klepp Sept. 5, 1944 The following references are of record in the 10 2,374,199 Harms 24, 1945 file 0f patent: pp June UNITED STATES PATENTS 2,4 ,866 Jewell Oct. 22, 1940 Number Name Date FOREIGN PATENTS 1,396,919 Brace Nov. 15, 1921 15 Number Country Date 1,449,897 Evans Mar. 27, 1923 333,727 Great Britain Aug. 21, 1930 

1. AN ELECTROLYTIC APPARATUS HAVING AT LEAST ONE CELL FOR CONTAINING AN ELECTROLYTE AND HAVING A PLURALITY OF UNITS EACH COMPRISING TWO ELECTRODES IMMERSED IN SAID ELECTROLYTE, ADJUSTING MEANS FOR MOVING ONE OF SAID ELECTRODES TOWARD AND AWAY FROM THE OTHER ELECTRODE, POWER LEADS ATTACHED TO SAID ELECTRODES FOR CONNECTION THROUGH A MAIN LEAD WITH A DIRECT-CURRENT SOURCE, A BALANCED RELAY IN EACH UNIT HAVING TWO INDUCTANCE MEMBERS WHOSE ELECTROMAGNETIC FIELDS ARE IN OPPOSITION AND A MEMBER ACTUATED BY SAID INDUCTANCE MEMBERS, SAID ACTUATED MEMBER MOVING BETWEEN A CONNECTION FOR CAUSING THE ADJUSTING MEANS TO MOVE THE SAID ONE ELECTRODE AWAY FROM THE OTHER ELECTRODE AND A CONNECTION FOR CAUSING SAID ADJUSTING MEANS TO MOVE THE SAID ONE ELECTRODE TOWARD THE OTHER ELECTRODE, MEANS COUPLED WITH THE POWER LEAD OF ONE OF SAID ELECTRODES FOR IMPRESSING ON ONE OF SAID INDUCTANCE MEMBERS A VOLTAGE PROPORTIONAL TO THE CURRENT FLOWING THROUGH SAID ELECTRODE, AND MEANS CONNECTED TO THE MAIN LEAD FOR IMPRESSING ON THE OTHER OF SAID INDUCTANCE MEMBERS A VOLTAGE PROPORTIONAL TO THE CURRENT FLOWING THROUGH ALL OF THE UNITS. 